Supercapacitor with biasing electrode

Abstract

An asymmetric supercapacitor having a positive electrode, a negative electrode and a biasing electrode disposed between the positive electrode and negative electrode. The biasing electrode accumulates a mass-balanced equivalent amount of charge as the supercapacitor is charging, and an independent voltage applied to the biasing electrode causes charge to be forced to the positive electrode or the negative electrode maintaining an equilibrium in the charge double layer.

I claim: 
     
       1. A supercapacitor comprising:
 a positive electrode; 
 a negative electrode; and 
 a biasing electrode disposed between the positive electrode and the negative electrode, wherein the biasing electrode is configured to store a charge. 
 
     
     
       2. The supercapacitor of  claim 1  wherein a first voltage applied to the biasing electrode is not electrically connected to a circuit of the positive electrode and negative electrode. 
     
     
       3. The supercapacitor of  claim 1  wherein the positive electrode and biasing electrode comprise the same material. 
     
     
       4. The supercapacitor of  claim 1  wherein the positive electrode comprises a first material and the negative electrode comprises the first material, with a different amount of the first material in each of the positive and negative electrodes such that the weight ratio of the positive electrode to the negative electrode is not 1:1. 
     
     
       5. The supercapacitor of  claim 4  wherein the first material comprises a carbon allotrope. 
     
     
       6. The supercapacitor of  claim 4  wherein the first material comprises activated charcoal and graphene nanoplatelets. 
     
     
       7. The supercapacitor of  claim 4  wherein the negative electrode further comprises a second material that is different from the first material. 
     
     
       8. The supercapacitor of  claim 7  wherein the second material in the negative electrode comprises lithiated graphite. 
     
     
       9. The supercapacitor of  claim 8  wherein the lithiated graphite in the negative electrode is about 10-40 wt %. 
     
     
       10. The supercapacitor of  claim 8  wherein an amount of lithiated graphite in the negative electrode is sufficient to produce an operating voltage greater than 4.5 V. 
     
     
       11. The supercapacitor of  claim 1 , wherein the biasing electrode is further configured to store a mass-balance equivalent amount of charge as the supercapacitor is charging. 
     
     
       12. A supercapacitor comprising:
 a positive electrode; 
 a negative electrode; and 
 a biasing electrode disposed between the positive electrode and the negative electrode wherein
 wherein the positive electrode comprises a first material and the negative electrode comprises the first material, with a different amount of the first material in each of the positive and negative electrodes such that the weight ratio of the positive electrode to the negative electrode is not 1:1. 
 
 
     
     
       13. The supercapacitor of  claim 12  wherein the first material is a carbon allotrope. 
     
     
       14. The supercapacitor of  claim 12  wherein the first material comprises activated charcoal and graphene nanoplatelets. 
     
     
       15. The supercapacitor of  claim 12  wherein the negative electrode further comprises lithiated graphite in an amount sufficient to produce an operating voltage greater than 4.5V. 
     
     
       16. A supercapacitor comprising:
 a positive electrode; 
 a negative electrode; and 
 a biasing electrode disposed between the positive electrode and the negative electrode and configured to store a charge, wherein a first voltage applied to the biasing electrode is independent of a second voltage applied to the positive electrode and negative electrode. 
 
     
     
       17. The supercapacitor of  claim 16  wherein:
 the positive electrode and biasing electrode each comprise:
 activated charcoal in a range of 50-70 wt %; and 
 graphene nanoplatelets in a range of 20-40 wt %; and 
 
 the negative electrode comprises:
 activated charcoal in a range of 20-40 wt %; 
 graphene nanoplatelets in a range of 10-30 wt %; and 
 lithiated graphite in a range of 10-40 wt %. 
 
 
     
     
       18. The supercapacitor of  claim 16  wherein the positive electrode and biasing electrode each comprise 60 wt % activated charcoal and 30 wt % graphene nanoplatelets. 
     
     
       19. The supercapacitor of  claim 18  wherein the negative electrode comprises 30 wt % activated charcoal, 20 wt % graphene nanoplatelets and 10-40 wt % lithiated graphene. 
     
     
       20. The supercapacitor of  claim 16  wherein:
 the positive electrode and biasing electrode each comprise:
 activated charcoal at about 60 wt %; and 
 graphene nanoplatelets at about 30 wt %; and 
 
 the negative electrode comprises:
 activated charcoal at about 30 wt %; 
 graphene nanoplatelets at about 20 wt %; and 
 lithiated graphite at about 10-40 wt % depending on a desired operating voltage.